Add hideCursor & showCursor

lib/pure/terminal.nim

@@ -13,6 +13,8 @@
 ## Windows API.
 ## Changing the style is permanent even after program termination! Use the
 ## code ``system.addQuitProc(resetAttributes)`` to restore the defaults.
+## Similarly, if you hide the cursor, make sure to unhide it with
+## ``showCursor`` before quitting.
 
 import macros
 
@@ -49,6 +51,10 @@ when defined(windows):
       srWindow: SMALL_RECT
       dwMaximumWindowSize: COORD
 
+    CONSOLE_CURSOR_INFO = object
+      dwSize: DWORD
+      bVisible: WINBOOL
+
   proc duplicateHandle(hSourceProcessHandle: HANDLE, hSourceHandle: HANDLE,
                        hTargetProcessHandle: HANDLE, lpTargetHandle: ptr HANDLE,
                        dwDesiredAccess: DWORD, bInheritHandle: WINBOOL,
@@ -60,6 +66,14 @@ when defined(windows):
     lpConsoleScreenBufferInfo: ptr CONSOLE_SCREEN_BUFFER_INFO): WINBOOL{.stdcall,
     dynlib: "kernel32", importc: "GetConsoleScreenBufferInfo".}
 
+  proc getConsoleCursorInfo(hConsoleOutput: HANDLE,
+      lpConsoleCursorInfo: ptr CONSOLE_CURSOR_INFO): WINBOOL{.
+      stdcall, dynlib: "kernel32", importc: "GetConsoleCursorInfo".}
+
+  proc setConsoleCursorInfo(hConsoleOutput: HANDLE,
+      lpConsoleCursorInfo: ptr CONSOLE_CURSOR_INFO): WINBOOL{.
+      stdcall, dynlib: "kernel32", importc: "SetConsoleCursorInfo".}
+
   proc terminalWidthIoctl*(handles: openArray[Handle]): int =
     var csbi: CONSOLE_SCREEN_BUFFER_INFO
     for h in handles:
@@ -179,6 +193,30 @@ else:
       return w
     return 80                               #Finally default to venerable value
 
+when defined(windows):
+  proc setCursorVisibility(f: File, visible: bool) =
+    var ccsi: CONSOLE_CURSOR_INFO
+    let h = conHandle(f)
+    if getConsoleCursorInfo(h, addr(ccsi)) == 0:
+      raiseOSError(osLastError())
+    ccsi.bVisible = if visible: 1 else: 0
+    if setConsoleCursorInfo(h, addr(ccsi)) == 0:
+      raiseOSError(osLastError())
+
+proc hideCursor*(f: File) =
+  ## Hides the cursor.
+  when defined(windows):
+    setCursorVisibility(f, false)
+  else:
+    f.write("\e[?25l")
+
+proc showCursor*(f: File) =
+  ## Shows the cursor.
+  when defined(windows):
+    setCursorVisibility(f, true)
+  else:
+    f.write("\e[?25h")
+
 proc setCursorPos*(f: File, x, y: int) =
   ## Sets the terminal's cursor to the (x,y) position.
   ## (0,0) is the upper left of the screen.
@@ -558,6 +596,8 @@ proc getch*(): char =
     discard fd.tcsetattr(TCSADRAIN, addr oldMode)
 
 # Wrappers assuming output to stdout:
+template hideCursor*() = hideCursor(stdout)
+template showCursor*() = showCursor(stdout)
 template setCursorPos*(x, y: int) = setCursorPos(stdout, x, y)
 template setCursorXPos*(x: int)   = setCursorXPos(stdout, x)
 when defined(windows):